using Dinah.Core;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;

namespace DataLayer;

public class AudibleProductId
{
	public string Id { get; }
	public AudibleProductId(string id)
	{
		ArgumentValidator.EnsureNotNullOrWhiteSpace(id, nameof(id));
		Id = id;
	}
}

// enum will be easier than bool to extend later. 
public enum ContentType
{
	Unknown = 0,
	Product = 1,
	Episode = 2,
	Parent = 4,
}


public class Book
{
	// implementation detail. set by db only. only used by data layer
	internal int BookId { get; private set; }

	// immutable
	public string AudibleProductId { get; private set; }
	public string Title { get; private set; }
	public string Subtitle { get; private set; }
	private string? _titleWithSubtitle;
	public string TitleWithSubtitle => _titleWithSubtitle ??= string.IsNullOrEmpty(Subtitle) ? Title : $"{Title}: {Subtitle}";
	public string Description { get; private set; }
	public int LengthInMinutes { get; private set; }
	public ContentType ContentType { get; private set; }
	public string Locale { get; private set; }

	// mutable
	public string? PictureId { get; set; }
	public string? PictureLarge { get; set; }

	// book details
	public bool IsAbridged { get; private set; }
	public bool IsSpatial { get; private set; }
	public DateTime? DatePublished { get; private set; }
	public string? Language { get; private set; }

	// is owned, not optional 1:1
	public UserDefinedItem UserDefinedItem { get; private set; }

	// is owned, not optional 1:1
	/// <summary>The product's aggregate community rating</summary>
	public Rating Rating { get; private set; } = new Rating(0, 0, 0);

	// ef-ctor
#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
	private Book() { }
#pragma warning restore CS8618
	// non-ef ctor
	/// <param name="audibleProductId">special id class b/c it's too easy to get string order mixed up</param>
	public Book(
			AudibleProductId audibleProductId,
			string? title,
			string? subtitle,
			string? description,
			int lengthInMinutes,
			ContentType contentType,
			IEnumerable<Contributor> authors,
			IEnumerable<Contributor> narrators,
			string localeName
			)
	{
		// validate
		ArgumentValidator.EnsureNotNull(audibleProductId, nameof(audibleProductId));
		var productId = audibleProductId.Id;
		ArgumentValidator.EnsureNotNullOrWhiteSpace(productId, nameof(productId));

		// assign as soon as possible. stuff below relies on this
		AudibleProductId = productId;
		Locale = localeName;

		ArgumentValidator.EnsureNotNullOrWhiteSpace(title, nameof(title));

		// non-ef-ctor init.s
		UserDefinedItem = new UserDefinedItem(this);
		ContributorsLink = new HashSet<BookContributor>();
		CategoriesLink = new HashSet<BookCategory>();
		_seriesLink = new HashSet<SeriesBook>();
		_supplements = new HashSet<Supplement>();

		// simple assigns

		Title = title?.Trim() ?? "";
		Subtitle = subtitle?.Trim() ?? "";
		Description = description?.Trim() ?? "";
		LengthInMinutes = lengthInMinutes;
		ContentType = contentType;

		// assigns with biz logic
		ReplaceAuthors(authors);
		ReplaceNarrators(narrators);
	}

	public void UpdateTitle(string? title, string? subtitle)
	{
		Title = title?.Trim() ?? "";
		Subtitle = subtitle?.Trim() ?? "";
		_titleWithSubtitle = null;
	}

	public void UpdateLengthInMinutes(int lengthInMinutes)
		=> LengthInMinutes = lengthInMinutes;

	#region contributors, authors, narrators
	internal HashSet<BookContributor> ContributorsLink { get; private set; }

	public IEnumerable<Contributor> Authors => ContributorsLink.ByRole(Role.Author).Select(bc => bc.Contributor).ToList();
	public IEnumerable<Contributor> Narrators => ContributorsLink.ByRole(Role.Narrator).Select(bc => bc.Contributor).ToList();
	public string? Publisher => ContributorsLink.ByRole(Role.Publisher).SingleOrDefault()?.Contributor.Name;

	public void ReplaceAuthors(IEnumerable<Contributor> authors, DbContext? context = null)
		=> replaceContributors(authors, Role.Author, context);
	public void ReplaceNarrators(IEnumerable<Contributor> narrators, DbContext? context = null)
		=> replaceContributors(narrators, Role.Narrator, context);
	public void ReplacePublisher(Contributor publisher, DbContext? context = null)
		=> replaceContributors(new List<Contributor> { publisher }, Role.Publisher, context);
	private void replaceContributors(IEnumerable<Contributor> newContributors, Role role, DbContext? context = null)
	{
		ArgumentValidator.EnsureEnumerableNotNullOrEmpty(newContributors, nameof(newContributors));

		// the edge cases of doing local-loaded vs remote-only got weird. just load it
		if (ContributorsLink is null)
		{
			if (context is null)
				throw new ArgumentNullException(nameof(context), "A DbContext is required to load the ContributorsLink collection");
			getEntry(context).Collection(s => s.ContributorsLink).Load();
		}

		var isIdentical
			= ContributorsLink
			!.ByRole(role)
			.Select(c => c.Contributor)
			.SequenceEqual(newContributors);

		if (isIdentical)
			return;

		ContributorsLink!.RemoveWhere(bc => bc.Role == role);
		addNewContributors(newContributors, role);
	}

	private void addNewContributors(IEnumerable<Contributor> newContributors, Role role)
	{
		byte order = 0;
		var newContributionsEnum = newContributors.Select(c => new BookContributor(this, c, role, order++));
		var newContributions = new HashSet<BookContributor>(newContributionsEnum);
		ContributorsLink.UnionWith(newContributions);
	}

	#endregion

	private Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry<Book> getEntry(DbContext context)
	{
		ArgumentValidator.EnsureNotNull(context, nameof(context));

		var entry = context.Entry(this);

		if (!entry.IsKeySet)
			throw new InvalidOperationException("Could not load a valid Book from database");

		return entry;
	}

	#region categories
	internal HashSet<BookCategory> CategoriesLink { get; private set; }

	private ReadOnlyCollection<BookCategory>? _categoriesReadOnly;
	public ReadOnlyCollection<BookCategory> Categories
	{
		get
		{
			if (_categoriesReadOnly?.SequenceEqual(CategoriesLink) is not true)
				_categoriesReadOnly = CategoriesLink.ToList().AsReadOnly();
			return _categoriesReadOnly;
		}
	}
	public void SetCategoryLadders(IEnumerable<CategoryLadder> ladders)
	{
		ArgumentValidator.EnsureNotNull(ladders, nameof(ladders));

		//Replace all existing category ladders.
		//Some books make have duplicate ladders
		CategoriesLink.Clear();
		CategoriesLink.UnionWith(ladders.Distinct().Select(l => new BookCategory(this, l)));
	}
	#endregion

	#region series
	private readonly HashSet<SeriesBook>? _seriesLink;
	public IEnumerable<SeriesBook> SeriesLink => _seriesLink?.ToList() ?? [];

	public void UpsertSeries(Series series, string? order, DbContext? context = null)
	{
		ArgumentValidator.EnsureNotNull(series, nameof(series));

		// our add() is conditional upon what's already included in the collection.
		// therefore if not loaded, a trip is required. might as well just load it
		if (_seriesLink is null)
		{
			if (context is null)
				throw new ArgumentNullException(nameof(context), "A DbContext is required to load the SeriesLink collection");
			getEntry(context).Collection(s => s.SeriesLink).Load();
		}

		var singleSeriesBook = _seriesLink!.SingleOrDefault(sb => sb.Series == series);
		if (singleSeriesBook is null)
			_seriesLink!.Add(new SeriesBook(series, this, order));
		else
			singleSeriesBook.UpdateOrder(order);
	}
	#endregion

	#region supplements
	private readonly HashSet<Supplement>? _supplements;
	public IEnumerable<Supplement> Supplements => _supplements?.ToList() ?? [];

	public void AddSupplementDownloadUrl(string url)
	{
		// supplements are owned by Book, so no need to Load():
		//  Are automatically loaded, and can only be tracked by a DbContext alongside their owner.

		ArgumentValidator.EnsureNotNullOrWhiteSpace(url, nameof(url));

		if (_supplements?.Any(s => url.EqualsInsensitive(url)) is true)
			return;

		_supplements?.Add(new Supplement(this, url));
		UserDefinedItem.PdfStatus ??= LiberatedStatus.NotLiberated;
	}
	#endregion

	public void UpdateProductRating(float overallRating, float performanceRating, float storyRating)
		=> Rating.Update(overallRating, performanceRating, storyRating);

	public void UpdateBookDetails(bool isAbridged, bool? isSpatial, DateTime? datePublished, string? language)
	{
		// don't overwrite with default values
		IsAbridged |= isAbridged;
		IsSpatial = isSpatial ?? IsSpatial;
		DatePublished = datePublished ?? DatePublished;
		Language = language?.FirstCharToUpper() ?? Language;
	}

	public override string ToString() => $"[{AudibleProductId}] {TitleWithSubtitle}";
}